Optical Resolution of dl-Phenylalanine with Acylase

New devices for resolution of DL-phenylalanine by an enzymatic method have been developed by using ammonium N-acetyl-DL-phenylalanate as a substrate. In this procedure, crystals of l-phenylalanine and ammonium N-acetyl-d-phenylalanate are separated alternately or simultaneously from reaction mixtures containing acylase, as first crops. The whole resulting solution including acylase can be reused. Ammonium acetate formed as a by-product was found to inhibit the enzyme.     

Location and State of Methionine Residues in a Papain-synthesized Plastein from a Mixture of Soybean Protein Hydrolysate and l-Methionine Ethyl Ester

With the aid of papain, a plastein was synthesized from a 1 : 10 mixture of l-methionine ethyl ester and a peptic hydrolysate of soybean protein. Dialysis of the whole reaction-product yielded a methionine-incorporated plastein (Met-plastein) as the nondialyzable fraction, its yield being 78.2% on a dry-matter basis, of the whole reaction-product. Methionine content in this Met-plastein was 7.22% on a weight basis, while its content in the material hydrolysate was only 1.25%. Carboxypeptidase A treatment of Met-plastein liberated methionine at an outstandingly rapid rate. A similar, but not so outstanding, rate was observed for the methionine liberation from Met-plastein by treatment with leucine aminopeptidase. Methyl isothiocyanate treatment and subsequent cyclization yielded a mixture of methylthiohydantoins from Met-plastein. Gas chromatographic analysis of this mixture after trimethylsilylation showed a result that methionine occupied 33.2%, on a molar basis, of the total N-terminal amino acids. Lithium borohydride reduction and 6 n hydrochloric, acid hydrolysis of Met-plastein produced monomeric aminois, and their 2,4-dinitrophenylation followed by thin-layer chromatography gave a result that methionine occupied 84.9%, on a molar basis, of the total C-terminal amino acids; the residues amounting to 14.4% of the C-terminal methionine residues remained as an ethyl eater form. The selective degradation probe employing cyanogen bromide to generate free homoserine disclosed that the occurrence of the polymeric methionine-methionine sequence was little if any in Met-plastein. Based on the above experiments as well as an evaluation of the esterase activity against l-methionine ethyl ester, a possible mechanism was discussed of the papain-catalyzed synthesis of plastein in a system containing such an ester.     

Correlation between the morpho-cytohistochemistry of the outer mantle epithelium of Anodonta cygnea with seasonal variations and following pollutant exposure

Seasonal and experimental conditions induce morphological and cytochemical variations in the outer mantle epithelium (OME) of the freshwater bivalve Anodonta cygnea, probably influencing the shell calcification mechanism. In this study, OME samples were taken from untreated animals in autumn, winter, spring and summer as well as from animals exposed to divalent metals (cadmium, chromium, lead, copper and zinc) and pesticides (setoxidim and dimethoate) and observed by light microscopy. The present results showed that OME cells have larger cell volumes and increased amounts of secreted macromolecules during spring and summer than in autumn and winter. This correlates with higher shell calcification rates in spring and summer and lower shell calcification rates in autumn and winter. The experiments showed that incubation with pollutants for 8 months dramatically reduced the cellular volume so that the density of cytoplasmic material appeared higher that in the control samples. The pronounced changes in OME cells suggest a significant decrease in secretory activity following exposure to toxic agents and this has implications for the shell calcification process.     

Mucin 20 modulates proteasome capacity through c-Met signalling to increase carfilzomib sensitivity in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a haematologic malignancy. The proteasome inhibitor (PI) bortezomib has been approved to treat MCL, but resistance has emerged through mechanisms that remain unclear. This study aimed to explore the mechanism of PI resistance in MCL and identify new targets for this patient subgroup. Carfilzomib-resistant (CR) MCL cell lines and primary samples were used for both in vitro and in vivo experiments to identify gene expression and explore their related signalling pathways. We first identified mucin 20 (MUC20) suppression in carfilzomib-resistant MCL models. MUC20 overexpression sensitized cells to carfilzomib in vitro and in vivo. MUC20 expression was inversely related to activation of c-Met and the downstream p44/42 MAPK pathway. c-Met activation with hepatocyte growth factor (HGF) induced PI resistance, while c-Met inhibition restored PI sensitivity. Carfilzomib resistance and depressed MUC20 expression were associated with enhanced proteasome activity and higher expression of proteassemblin (POMP), a chaperone for catalytically active proteasome assembly. c-Met and POMP were associated through binding and induction of MAPK-regulated ELK1 to the POMP promoter. Our data reveal that c-Met signalling activation enhanced proteasome capacity as a mechanism of PI resistance, and MUC20 expression may be a useful biomarker for PI therapy.     

Zona Localization of Shell Matrix Proteins in Mantle of <Emphasis Type="Italic">Haliotis tuberculata</Emphasis> (Mollusca,Gastropoda)

Organic matrix from molluscan shells has the potential to regulate calcium carbonate deposition and crystallization. Control of crystal growth thus seems to depend on control of matrix protein secretion or activation processes in the mantle cells, about which little is known. Biomineralization is a highly orchestrated biological process. The aim of this work was to provide information about the source of shell matrix macromolecule production, within the external epithelium of the mantle. An in vivo approach was chosen to describe the histologic changes in the outer epithelium and in blood sinus distribution, associated with mantle cells implicated in shell matrix production. Our results characterized a topographic and time-dependent zonation of matrix proteins involved in shell biomineralization in the mantle of Haliotis.     

H+-ATPase of crude homogenate of the outer mantle epithelium of Anodonta cygnea

The outer mantle epithelium of the freshwater bivalve, Anodonta cygnea, is responsible for the mineralisation of the shell. Under short circuit conditions, it generates a current that is due to the operation of an electrogenic proton pump located in the apical barrier of that epithelium. Bafilomycin A1 and Concanamycin A inhibited the short circuit current. The IC50 and maximum inhibition dose were 0.17 and 0.5 microM for Bafilomycin A1, and 0.7 and 5 microM for Concanamycin A. The present work was undertaken to further characterise V-type ATPase of the outer mantle cells. The V-ATPase enzymatic activity of crude homogenate, measured as the amount of inorganic phosphorous released, due to ATP hydrolysis, in the presence of Na2SO3 (200 mM) was found to be 4.6+/-1.1 micromol Pi/mg protein/h, at 27 degrees C, pH 7.0-7.4 and ATP 4.5-6.0 microM. Bafilomycin A1 and Concanamycin A inhibit the V-ATPase activity with an IC50 of 14 and 8 nmol mg(-1), respectively. Dicyclohexylcarbodiimide (DCCD; 100 mM) and NaNO3 (100 microM) inhibited the V-type ATPase in what it seems a non-specific manner and NEM (100 mM) was unable to do it. Bafilomycin A1 (10 microM) and Concanamycin A (10 microM), inhibited 50-60% of the total activity.     

A novel respiratory architecture in the Silurian mollusc Acaenoplax

Extant aplacophorans, a group of shell‐less vermiform molluscs, respire through appendages within or projecting from a posterior cavity. Respiratory structures differ between the subclasses Caudofoveata (ctenidia within the cavity) and Solenogastres (folds of the mantle itself). Acaenoplax hayae, a Silurian vermiform mollusc from the Herefordshire Lagerstätte, England, exhibits characteristics of both these groups. While recent work places it within the crown group Aplacophora, near the caudofoveates, initial observations suggested that its respiratory structures were closer to those of the solenogastres. Here, we present new reconstructions of the posterior of Acaenoplax prepared with the aim of resolving features obscured when prior studies were undertaken. These reconstructions detail a novel posterior architecture, not closely comparable to that of either extant aplacophoran group, in which respiratory projections arise from a membrane that partly encloses a central posterior cavity. The posterior membrane is flanked by small spherical projections; both membrane and spherical projections are apparently unique within the Aplacophora. The existence of this previously undocumented respiratory system underlines the diversity of the aplacophoran clade during the Palaeozoic.     

黄土丘陵区三种典型土壤地类造林技术

中国黄土高原丘陵沟壑区是世界上水土流失最严重的区域之一,由于长期水土流失的侵蚀切割作用,表层土壤流失殆尽,黄绵土母质、红胶泥土以及土壤与岩石过渡类型--风化岩沫土等土壤类型依次裸露了出来,形成了3种典型的土壤地类,增加了造林的难度.由于红胶泥与风化岩沫土土壤瘠薄,当地林业部门认为这两种土壤地类不能造林,因此,传统造林只在黄棉土进行.为此,提出了＂适土适树,因土制宜＂的造林原则和＂穴衬膜栽植技术＂,以扩大适宜造林的土壤类型.穴衬膜栽植技术是指树木栽植时,在挖好的栽树坑底部和四周衬贴一层防渗薄膜（厚度为0.0007 mm可降解塑料薄膜）,树木栽好覆土浇水后,再在地表面覆膜,防止栽树浇水（施肥）的渗漏和蒸发,使树根在较长时间内处于含水量较高、四周封闭的潮湿土壤之中,从而达到提高成活率和促进林木前期生长的目的.1997～2001年,我们在黄土丘陵区陕西省延安市下砭沟小流域采用田间对比试验法进行了5年试验,结果表明,穴衬膜栽植技术促进浅层根系的生长发育,保水作用可持续4个月以上,对各种树木成活率和生长量均有显著促进作用,在黄土丘陵地区这3种土壤地类采用穴衬膜栽植技术可达到良好的造林效果,特别是红胶泥和风化岩沫土地类主要位于沟谷两岸,地下水供给较为充裕,是浅根性植物生长发育的良好土壤类型,科学混交可获得更好效果.